Snapshot sync (#2047)

* PV64 sync

* Tests

* Client DB restore

* Snapshot restoration over IPC

* Upating test

* Minor tweaks

* Upating test

ethcore/src/verification/mod.rs

@@ -25,7 +25,7 @@ pub use self::canon_verifier::CanonVerifier;
 pub use self::noop_verifier::NoopVerifier;
 
 /// Verifier type.
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Clone)]
 pub enum VerifierType {
 	/// Verifies block normally.
 	Canon,